The inventive concept relates generally to seed controllers and operating methods for seed controllers. More particularly, the inventive concept relates to seed controllers and seed controller operating methods used in memory systems including nonvolatile memory device.
Programmed memory cells in contemporary nonvolatile memory devices are subject to many system and environmental influences capable of changing the data state of the memory cells. For example, in flash memory devices, memory cells may be collectively or respectively affected by program voltage disturbances, pass voltage disturbances, bit-line and/or word-line coupling effects, back pattern dependencies, etc. One or more of these “influences” may cause an undesired state change in a programmed memory cell.
It has been noted that randomized data stored in a memory cell array is less likely to be adversely affected by ill influences, as compared with patterned data (i.e., input data having a substantially non-random pattern of digital data values). Accordingly, input data is often randomized before being programmed to a nonvolatile memory cell array to improve data reliability.
One type of randomizer uses a so-called pseudo-noise (PN) sequence to randomize input data. A linear feedback shift register (LFSR) may be used to generate a PN sequence from an initial value called a “seed”.